1. Field of the Invention
The present invention relates to a motor driving apparatus.
2. Description of the Related Art
With the speeding up of personal computers and workstations of recent years, operation speeds of LSIs (Large Scale Integrated circuits) for computation, such as CPUs (Central Processor Units), DSPs (Digital Signal Processors), and the like, are increasing.
In such LSIs, as the operation speeds thereof, that is, clock frequencies, become higher, generated amounts of generated heat become large. There is a problem in that the generated heat from an LSI leads to thermorunaway of the LSI itself, or has an impact on surrounding circuits. Consequently, appropriate thermal cooling of LSIs is a very important technology.
As one example of technology for cooling an LSI, there is a cooling method of air-cooling by a cooling fan. In this method, for example, the cooling fan is arranged opposite a surface of the LSI, and cooling air is blown on the LSI surface by the cooling fan. When the LSI is cooled by such a cooling fan, temperature near the LSI is monitored and level of cooling is adjusted by changing rotation of the fan in accordance with the temperature thereof (Patent Documents 1 and 2).
Patent Document 1: Japanese Patent Application, Laid Open No. H7-31190
Patent Document 2: Japanese Patent Application, Laid Open No. 2001-284868
However, there are cases in which the generated amounts of heat of an LSI, the temperature thereof, a threshold temperature for thermorunaway, and the like, differ for every LSI. Consequently, it is desirable to be able to flexibly set rotation speed of a cooling fan in accordance with an LSI that is to be cooled.